Rocking fulcrum member

ABSTRACT

The crisscross fulcrum according to the present invention is formed as a continuous member by fabricating one elastic member in the form of a plate. Therefore, the rocking fulcrum member can be obtained as a precise fulcrum member at a low cost with reduced variations in the spring characteristic and can be easily assembled. Additionally, in the present invention, it is preferable that a heat treatment should be performed on the crisscross spring formed by fabricating the one elastic member in the form of a plate. By the heat treatment performed after fabricating for forming the crisscross spring, the spring characteristic is improved.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a rocking fulcrum member and, moreparticularly, to a crisscross-spring-type rocking fulcrum member used ina lever-type detector or the like.

2. Description of the Related Art

In lever-type detectors or the like, a finger arm having a contactorattached to its tip is supported on a rocking fulcrum so as to be ableto seesaw. The detector detects the amount of movement of the finger armwhen the contactor is in contact with a work.

Examples of rocking fulcrum members used in such detectors are anelastic fulcrum such as shown in FIG. 7C, an L-shaped spring fulcrumsuch as shown in FIG. 7B, a bearing (not shown) and crisscross springfulcrums such as shown in FIG. 7A. Elastic fulcrums are capable ofoperating with accuracy but can be used only in a case where themeasurement range is narrow because they have only restricted swingangles.

L-shaped spring fulcrums are low-priced and are being widely used buthave a drawback in that the fulcrum center is shifted with a swingingmovement and cannot be suitably used as a precise fulcrum member.Bearing fulcrums can have any swing angle but need periodicalreplacement because their accuracy is reduced due to wear.

Crisscross spring fulcrums include those formed by disposing two platesprings so that the plate springs cross each other as shown on theleft-hand side of FIG. 7A, and those integrally formed by being cut bywire cutting as shown on the right-hand side of FIG. 7A. The latter havesufficient rigidity and high accuracy during repeated use and cantherefore be suitably used as a precise fulcrum.

A crisscross spring fulcrum such as shown on the left-hand side of FIG.7A is fixed by screwing opposite ends of the two plate springs tomembers or by welding the opposite ends to the members. A method ofdie-casting a crisscross spring base member and embedding the oppositeends of the two plate springs in the crisscross spring base member atthe time of casting is also used (see, for example, WO 98/20297pamphlet).

A crisscross spring fulcrum having two plate springs welded to groovesin a cylindrical housing has also been proposed (see, for example, U.S.Pat. No. 3,807,029).

In assembly of the above-described crisscross spring fulcrum memberfixed by screwing opposite ends of the two plate springs to members hasproblems that a considerably long time is required for assembly andvariations in spring characteristic occur due to assembly errors. Thecrisscross spring fulcrum having two plate springs embedded in acrisscross spring base member by die casting as described in WO 98/20297pamphlet and the crisscross spring fulcrum having two plate springsfixed to a base member by welding as described in U.S. Pat. No.3,807,029 have a problem that a considerably long time is required forfabricating and the assembly and manufacturing costs are high andanother problem that the plate springs are heated at a high temperatureat the time of welding or die casting to degrade the springcharacteristic.

The crisscross spring fulcrum integrally formed by cutting using wirecutting electrodischarge machining also has a problem that aconsiderably long time is required for fabricating and the manufacturingcost is high and another problem that the characteristic of the springdegrades with time due to microcracks caused by machining.

SUMMARY OF THE INVENTION

In view of the above-described circumstances, an object of the presentinvention is to provide a rocking fulcrum member having a crisscrossspring fulcrum, capable of being manufactured at a low cost with reducedvariations in the spring characteristic, and capable of being easilyassembled.

To achieve the above-described object, according to a first aspect ofthe present invention, there is provided a rocking fulcrum member,comprising: a first elastic plate portion and a second elastic plateportion placed on planes intersecting each other to form a crisscrossspring, wherein each of the first elastic plate portion and the secondelastic plate portion has extensions from its one end and the other endin its longitudinal direction; the extension from the one end of thefirst elastic plate portion is bent at an acute angle from the firstelastic plate portion, while the extension from the other end of thefirst elastic plate portion is bent at an obtuse angle from the firstelastic plate portion; the extension from the one end of the secondelastic plate portion is bent at an obtuse angle from the second elasticplate portion, while the extension from the other end of the secondelastic plate portion is bent at an acute angle from the second elasticplate portion; the extension from the one end of the first elastic plateportion and the extension from the one end of the second elastic plateportion are formed as one continuous member on one plane; the extensionfrom the other end of the first elastic plate portion and the extensionfrom the other end of the second elastic plate portion are formed as onecontinuous member on one plane; and the first elastic plate portion, theextension from the one end of the first elastic plate portion, theextension from the other end of the first elastic plate portion, thesecond elastic plate portion, the extension from the one end of thesecond elastic plate portion and the extension from the other end of thesecond elastic plate portion are a continuous member formed byfabricating one elastic member in the form of a plate.

In the first aspect of the present invention, it is preferable that awidth of the first elastic plate portion and a width of the secondelastic plate portion should be equal to each other.

To achieve the above-described object, according to a second aspect ofthe present invention, there is provided a rocking fulcrum member,comprising: a first elastic plate portion, a second elastic plateportion and a third elastic plate portion, the first elastic plateportion and the third elastic plate portion being placed parallel toeach other on one plane, the second elastic plate portion being placedbetween the first elastic plate portion and the third elastic plateportion, the first elastic plate portion, the third elastic plateportion and the second elastic plate portion being placed on planesintersecting each other to form a crisscross spring, wherein each of thefirst elastic plate portion, the second elastic plate portion and thethird elastic plate portion has extensions from its one end and theother end in its longitudinal direction; the extension from the one endof the first elastic plate portion is bent at an acute angle from thefirst elastic plate portion, while the extension from the other end ofthe first elastic plate portion is bent at an obtuse angle from thefirst elastic plate portion; the extension from the one end of thesecond elastic plate portion is bent at an obtuse angle from the secondelastic plate portion, while the extension from the other end of thesecond elastic plate portion is bent at an acute angle from the secondelastic plate portion; the extension from the one end of the thirdelastic plate portion is bent at an acute angle from the third elasticplate portion, while the extension from the other end of the thirdelastic plate portion is bent at an obtuse angle from the third elasticplate portion; the extension from the one end of the first elastic plateportion, the extension from the one end of the second elastic plateportion and the extension from the one end of the third elastic plateportion are formed as one continuous member on one plane; the extensionfrom the other end of the first elastic plate portion, the extensionfrom the other end of the second elastic plate portion and the extensionfrom the other end of the third elastic plate portion are formed as onecontinuous member on one plane; and the first elastic plate portion, theextension from the one end of the first elastic plate portion, theextension from the other end of the first elastic plate portion, thesecond elastic plate portion, the extension from the one end of thesecond elastic plate portion, the extension from the other end of thesecond elastic plate portion, the third elastic plate portion, theextension from the one end of the third elastic plate portion and theextension from the other end of the third elastic plate portion are acontinuous member formed by fabricating one elastic member in the formof a plate.

In the second aspect of the present invention, it is preferable that sumof a width of the first elastic plate portion and a width of the thirdelastic plate portion should be equal to a width of the second elasticplate portion.

In the first or the second aspect of the present invention, it ispreferable that an attachment hole for attachment of a member should beformed in each of the continuous member on one plane in which theextension from the one end of each elastic plate portion is formed andthe continuous member on one plane in which the extension from the otherend of each elastic plate portion is formed.

According to the present invention, the crisscross fulcrum is formed asa continuous member by fabricating one elastic member in the form of aplate. Therefore, the rocking fulcrum member can be obtained as aprecise fulcrum member at a low cost with reduced variations in thespring characteristic and can be easily assembled.

In the first or the second aspect of the present invention, it ispreferable that a heat treatment should be performed on the crisscrossspring formed by fabricating the one elastic member in the form of aplate. By the heat treatment performed after fabricating for forming thecrisscross spring, the spring characteristic is improved.

As described above, the crisscross fulcrum in the rocking fulcrum memberof the present invention is formed as a continuous member by fabricatingone elastic member in the form of a plate and, therefore, the rockingfulcrum member can be obtained as a precise fulcrum member at a low costwith reduced variations in the spring characteristic and can be easilyassembled.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a rocking fulcrum member according to anembodiment of the present invention;

FIG. 2 is a side view of the rocking fulcrum member according to theembodiment of the present invention;

FIG. 3 is a plan view of the rocking fulcrum member before forming;

FIG. 4 is a perspective view of an example of a modification of theembodiment;

FIG. 5 is a plan view of the rocking fulcrum member in the modificationof the embodiment before forming;

FIG. 6 is a sectional side view of an example of an application of therocking fulcrum member of the present invention; and

FIGS. 7A to 7C are perspective views of conventional rocking fulcrummembers.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A preferred embodiment of a rocking fulcrum member in accordance withthe present invention will be described in detail with reference to theaccompanying drawings. In the drawings, the same portions or componentsare indicated by the same reference numerals or symbols.

FIG. 1 is a perspective view of an embodiment of a rocking fulcrummember in accordance with the present invention, and FIG. 2 is a sideview of the embodiment. As shown in FIGS. 1 and 2, the rocking fulcrummember 10 has a first elastic plate portion 10A and a second elasticplate portion 10B. The surfaces of the first elastic plate portion 10Aand the second elastic plate portion 10B cross each other at rightangles to form a crisscross spring 11.

An extension 10C from one end of the first elastic plate portion 10A isbent at 45° from the first elastic plate portion 10A, while an extension10D from the other end of the first elastic plate portion 10A is bent at135° from the first elastic plate portion 10A.

An extension 10E from one end of the second elastic plate portion 10B isbent at 135° from the second elastic plate portion 10B, while anextension 10F from the other end of the second elastic plate portion 10Bis bent at 45° from the second elastic plate portion 10B.

The extension 10C from one end of the first elastic plate portion andthe extension 10E from one end of the second elastic plate portion areformed integrally with each other to form one L-shaped flat plate, andthe extension 10D from the other end of the first elastic plate portionand the extension 10F from the other end of the second elastic plateportion are also formed integrally with each other to form one L-shapedflat plate. Three attachment holes 10G for attachment of a member areformed in each L-shaped flat plate.

In the rocking fulcrum member 10 having the above-described structure,the L-shaped flat plate portions are parallel to each other in a no-loadcondition. When a force is applied to the L-shaped flat plate portionsin such a direction that the L-shaped flat plate portions are broughtcloser to each other or moved away from each other, rocking on thecrisscross fulcrum formed by the first elastic plate portion 10A and thesecond elastic plate portion 10B is caused.

The rocking fulcrum member 10 is integrally formed into a state shown inFIGS. 1 and 2 from one elastic plate member 50 shown in FIG. 3. Alarge-size elastic plate member is first punched with a punching pressto form the elastic plate member 50, six attachment holes 10G and acentral slit 50A, and the elastic plate member 50 is thereafterpress-formed so as to be bent through predetermined angles at positionsindicated by dotted lines in FIG. 3. A heat treatment is performed onthe formed member to improve the spring characteristic.

The width L1 of the first elastic plate portion and the width L2 of thesecond elastic plate portion are equal to each other and the precisecrisscross spring fulcrum is formed in a torsion-free condition.

FIG. 4 is a perspective view showing an example of a modification of theembodiment of the rocking fulcrum member in accordance with the presentinvention. A rocking fulcrum member 20 has a first elastic plate portion20A, a second elastic plate portion 20B and a third elastic plateportion 20H. The first elastic plate portion 20A and the third elasticplate portion 20H are placed parallel to each other with a certainspacing provided therebetween. The second elastic plate portion 20B isplaced between the first elastic plate portion 20A and the third elasticplate portion 20H.

The surfaces of the first elastic plate portion 20A, the third elasticplate portion 20H and the second elastic plate portion 20B cross eachother at right angles to form a crisscross spring 21.

An extension 20C from one end of the first elastic plate portion 20A isbent at 45° from the first elastic plate portion 20A, while an extension20D from the other end of the first elastic plate portion 20A is bent at135° from the first elastic plate portion 20A.

An extension 20E from one end of the second elastic plate portion 20B isbent at 135° from the second elastic plate portion 20B, while anextension 20F from the other end of the second elastic plate portion 20Bis bent at 45° from the second elastic plate portion 20B.

Further, an extension 20J from one end of the third elastic plateportion 20H is bent at 45° from the third elastic plate portion 20H,while an extension 20K (shown in FIG. 5 referred to below) from theother end of the third elastic plate portion 20H is bent at 135° fromthe third elastic plate portion 20H.

The extension 20C from one end of the first elastic plate portion, theextension 20E from one end of the second elastic plate portion and theextension 20J from one end of the third elastic plate portion are formedintegrally with each other to form one generally concave flat plate, andthe extension 20D from the other end of the first elastic plate portion,the extension 20F from the other end of the second elastic plate portionand the extension 20K from the third elastic plate portion are alsoformed integrally with each other to form one generally convex flatplate. Four attachment holes 20G for attachment of a member in theconcave flat plate, and three attachment holes 20G for attachment of amember in the convex flat plate are formed.

In the rocking fulcrum member 20 having the above-described structure,the generally concave flat plate portions and the generally convex flatplate portions are parallel to each other in a no-load condition, as arethe corresponding portions of the above-described rocking fulcrum member10. When a force is applied to the generally concave flat plate portionsin such a direction that the generally convex flat plate portions arebrought closer to each other or moved away from each other, rocking onthe crisscross fulcrum formed by the first elastic plate portion 20A,the third elastic plate portion 20H and the second elastic plate portion20B is caused.

The rocking fulcrum member 20 is integrally formed into a state shown inFIG. 4 from one elastic plate member 60 shown in FIG. 5, as is theabove-described rocking fulcrum member 10. A large-size elastic platemember is first punched with a punching press to form the elastic platemember 60, seven attachment holes 20G and two central slits 60A, and theelastic plate member 60 is thereafter press-formed so as to be bentthrough predetermined angles at positions indicated by dotted lines inFIG. 5. A heat treatment is performed on the formed member to improvethe spring characteristic.

The width L3 of the first elastic plate portion and the width L5 of thethird elastic plate portion are equal to each other and the sum of thewidth L3 of the first elastic plate portion and the width L5 of thethird elastic plate portion is equal to the width L4 of the secondelastic plate portion. The precise crisscross fulcrum is formed in atorsion-free condition.

FIG. 6 shows an example of an application of the rocking fulcrum member10 in accordance with the present invention to a rocking fulcrum for ameasuring head 80. In the measuring head 80, one of the L-shaped flatplate portions of the rocking fulcrum member 10 is screwed to ameasuring head body 81 by using the three attachment holes 10G and anattachment plate 82 having three threaded holes, as shown in FIG. 6.

An arm member 83 is screwed to the other L-shaped flat plate portion ofthe rocking fulcrum member 10 by using another attachment plate 82. Afinger 84 is attached to a fore end of the arm member 83. A contactor 85is attached to a tip of the finger 84. A core 86 of a differentialtransformer is attached to a rear end of the arm member 83. A coil 87 ofthe differential transformer is attached to the measuring head body 81.

A compression coil spring 88 is provided between the measuring head body81 and the arm member 83 to apply a measuring pressure to the contactor85. A stopper screw provided in the measuring head body 81 is used toset a rocking lower end of the arm member 83.

In the measuring head 80 having the above-described structure, the armmember 83 seesaws on the crisscross spring fulcrum formed by the rockingfulcrum member 10. The amount of movement of the contactor 85 when thecontactor 85 is in contact with a work is detected with the differentialtransformer, thus making an accurate measurement.

The rocking fulcrum member 10 is a press-formed crisscross springfulcrum member integrally formed as described above. Therefore, therocking fulcrum member 10 can be manufactured at a low cost and easilymounted, are free from variations in crisscross spring fulcrumcharacteristic due to variations in the mounted state and can besuitably used as a precise rocking fulcrum.

In the above-described embodiment, the crisscross spring in which thesurfaces of the first elastic plate spring portion 10A and the secondelastic plate spring portion 10B cross each other at right angles isformed. In the example of modification of the embodiment, the crisscrossspring in which the surfaces of the first elastic plate spring portion20A, the third elastic plate spring portion 20H and the second elasticplate spring portion 20B cross each other at right angles is formed.However, the crossing angle between these portions in the arrangement ofthe present invention may be different from 90°.

1. A rocking fulcrum member, comprising: a first elastic plate portion; and a second elastic plate portion placed on planes intersecting each other to form a crisscross spring, wherein each of the first elastic plate portion and the second elastic plate portion has extensions from its one end and the other end in its longitudinal direction; the extension from the one end of the first elastic plate portion is bent at an acute angle from the first elastic plate portion, while the extension from the other end of the first elastic plate portion is bent at an obtuse angle from the first elastic plate portion; the extension from the one end of the second elastic plate portion is bent at an obtuse angle from the second elastic plate portion, while the extension from the other end of the second elastic plate portion is bent at an acute angle from the second elastic plate portion; the extension from the one end of the first elastic plate portion and the extension from the one end of the second elastic plate portion are formed as one continuous member on one plane; the extension from the other end of the first elastic plate portion and the extension from the other end of the second elastic plate portion are formed as one continuous member on one plane; and the first elastic plate portion, the extension from the one end of the first elastic plate portion, the extension from the other end of the first elastic plate portion, the second elastic plate portion, the extension from the one end of the second elastic plate portion and the extension from the other end of the second elastic plate portion are a continuous member formed by fabricating one elastic member in the form of a plate.
 2. A rocking fulcrum member, comprising: a first elastic plate portion, a second elastic plate portion, and a third elastic plate portion, the first elastic plate portion and the third elastic plate portion being placed parallel to each other on one plane, the second elastic plate portion being placed between the first elastic plate portion and the third elastic plate portion, the first elastic plate portion, the third elastic plate portion and the second elastic plate portion being placed on planes intersecting each other to form a crisscross spring, wherein each of the first elastic plate portion, the second elastic plate portion and the third elastic plate portion has extensions from its one end and the other end in its longitudinal direction; the extension from the one end of the first elastic plate portion is bent at an acute angle from the first elastic plate portion, while the extension from the other end of the first elastic plate portion is bent at an obtuse angle from the first elastic plate portion; the extension from the one end of the second elastic plate portion is bent at an obtuse angle from the second elastic plate portion, while the extension from the other end of the second elastic plate portion is bent at an acute angle from the second elastic plate portion; the extension from the one end of the third elastic plate portion is bent at an acute angle from the third elastic plate portion, while the extension from the other end of the third elastic plate portion is bent at an obtuse angle from the third elastic plate portion; the extension from the one end of the first elastic plate portion, the extension from the one end of the second elastic plate portion and the extension from the one end of the third elastic plate portion are formed as one continuous member on one plane; the extension from the other end of the first elastic plate portion, the extension from the other end of the second elastic plate portion and the extension from the other end of the third elastic plate portion are formed as one continuous member on one plane; and the first elastic plate portion, the extension from the one end of the first elastic plate portion, the extension from the other end of the first elastic plate portion, the second elastic plate portion, the extension from the one end of the second elastic plate portion, the extension from the other end of the second elastic plate portion, the third elastic plate portion, the extension from the one end of the third elastic plate portion and the extension from the other end of the third elastic plate portion are a continuous member formed by fabricating one elastic member in the form of a plate.
 3. The rocking fulcrum member according to claim 2, wherein sum of a width of the first elastic plate portion and a width of the third elastic plate portion is equal to a width of a second elastic plate portion.
 4. The rocking fulcrum member according to claim 2, wherein an attachment hole for attachment of a member is formed in each of the continuous member on a plane in which the extension from the first end of each elastic plate portion is formed and the continuous member on a plane in which the extension from the second end of each elastic plate portion is formed.
 5. The rocking fulcrum member according to claim 3, wherein an attachment hole for attachment of a member is formed in each of the continuous member on a plane in which the extension from the first end of each elastic plate portion is formed and the continuous member on a plane in which the extension from the second end of each elastic plate portion is formed.
 6. The rocking fulcrum member according to claim 2, wherein a heat treatment is performed on the crisscross spring formed by fabricating the one elastic member in the form of a plate.
 7. The rocking fulcrum member according to claim 3, wherein a heat treatment is performed on the crisscross spring formed by fabricating the one elastic member in the form of a plate.
 8. The rocking fulcrum member according to claim 4, wherein a heat treatment is performed on the crisscross spring formed by fabricating the one elastic member in the form of a plate.
 9. The rocking fulcrum member according to claim 5, wherein a heat treatment is performed on the crisscross spring formed by fabricating the one elastic member in the form of a plate.
 10. A rocking fulcrum member, comprising: at least two elastic plate portions which are arranged serially with an odd number elastic plate portion and an even number elastic plate portion being located on planes that intersect each other to form a cross spring, wherein each of the elastic plate portions has an extension extending in a longitudinal direction from each of first and second ends thereof; wherein the extension extending from the first end of each odd number elastic plate portion is bent at an acute angle from the odd number elastic plate portion from which it extends while the extension extending from the second end of each odd number elastic plate portion is bent at an obtuse angle from the odd number elastic plate portion from which it extends; wherein the extension extending from the first end of each even number elastic plate portion is bent at an obtuse angle from the even number elastic plate portion from which it extends while the extension extending from the second end of each even number elastic plate portion is bent at an acute angle from the even number elastic plate portion from which it extends; wherein the extension from the first end of the odd number elastic plate portion and the extension from the first end of the even number elastic plate portion are formed as a continuous member on one plane; wherein the extension from the second end of the odd number elastic plate portion and the extension from the second end of the even number elastic plate portion are formed as one continuous member on one plane; and wherein the odd number elastic plate portion, the extension from the first end of the odd number elastic plate portion, the extension from the second end of the odd number elastic plate portion, the even number elastic plate portion, the extension from the first end of the even number elastic plate portion and the extension from the second end of the even number elastic plate portion are a continuous member fabricated from a plate.
 11. The rocking fulcrum member, according to claim 10, wherein a width of the odd elastic plate portion and a width of the even elastic plate portion are equal to each other.
 12. The rocking fulcrum member according to claim 10, wherein an attachment hole for attachment of a member is formed in each of the continuous member on plane in which the extension from the first end of each elastic plate portion is formed and the continuous member on plane in which the extension from the second end of each elastic plate portion is formed.
 13. The rocking fulcrum member according to claim 11, wherein an attachment hole for attachment of a member is formed in each of the continuous member on one plane in which the extension from the one end of each elastic plate portion is formed and the continuous member on one plane in which the extension from the other end of each elastic plate portion is formed.
 14. The rocking fulcrum member according to claim 10, wherein a heat treatment is performed on the cross spring formed by fabricating the elastic member from a plate.
 15. The rocking fulcrum member according to claim 11, wherein a heat treatment is performed on the crisscross spring formed by fabricating the one elastic member in the form of a plate.
 16. The rocking fulcrum member according to claim 12, wherein a heat treatment is performed on the cross spring formed by fabricating the elastic member from a plate.
 17. The rocking fulcrum member according to claim 13, wherein a heat treatment is performed on the crisscross spring formed by fabricating the one elastic member in the form of a plate. 